Your little fur ball wont stop biting because he/she is a rodent. Rodents bite, is what they do by instincts. Perhaps you're holding it too much. I think Guinea Pigs are gorgeous creatures and would love to own one.
I used to have white mice as pets some years back. They chewed on anything they could. They are so sweet but biting is something they will never stop doing. They do it because their teeth are constantly growing.
"When choosing floor linings and cage furnishings, keep in mind that guinea pigs will chew on just about anything to wear down their constantly growing teeth, so everything placed in the cage must be nontoxic."
Take a look at this page/guide: